Authentication vs Authorization

In web development, two crucial concepts often get tangled: authentication and authorization. While they sound similar and are both essential for securing applications, they serve distinct purposes.

Authentication is the process of verifying a user's identity. It answers the question: "Are you who you say you are?"

• Purpose: Confirm identity
• Common methods:
  • Username + password
  • OTP (One-Time Password)
  • Biometric data (fingerprint, face recognition)
  • OAuth (e.g., logging in via Google or Facebook)
• Example: When a user logs into a site using their credentials, the system checks if those credentials match a known user

Authorization determines what an authenticated user is allowed to do. It answers: "Do you have permission to access this resource?"

• Purpose: Grant or deny access to specific resources or actions
• Common mechanisms:
  • Role-based access control (RBAC)
  • Permission flags (e.g., isAdmin, canEdit)
  • Access tokens with scopes
• Example: After logging in, a user may be allowed to view their profile but not access admin settings